Got it.
Covers will help with comfort and sweating (keeps the pads clean)...but don't think they will make your pads last longer. I have an AKG K553 which I never use. I stored it in my closet years ago-- it is a backup to my T5p. A month or so ago I remembered I had it in there and I took it out just for the hell of it...and this is how I found the pads:
I checked my TH-X00 (a backup to my D2000) and those pads had also started to flake. I continued the inspection and I found that my HD800 pads had started to disintegrate ( I do use that one, just never noticed). After 4 or 5 years, pleather pads will just fall apart.
I replaced all the pleather pads with leather (Dekoni, ZMF, Brainwaz). I spent around $400...ouch.
The AKG is back in the closet, this time with sheepskin pads.